Dr. Leo Rodriguez of Los Angeles County-USC Medical Center said eight people in all needed immediate medical attention after they were taken off the bus Thursday, the Los Angeles Times reported. It was not clear Thursday afternoon how many people in all sustained injuries but officials said at least 30 and perhaps as many as 50 people had injuries ranging from "pretty basic blunt-force trauma" to cuts and bruises.
Rodriguez told reporters at a news conference he had treated patients ranging in age from 60 to 80 years old.
The bus was operated by Da Zhen, which KNBC-TV, Los Angeles, described as a Chinese company that runs day trips to Las Vegas.
It was carrying passengers to San Manuel Indian Bingo and Casino in Highland, Calif., after picking up an undetermined number of passengers in Monterey Park and San Gabriel, the Times said.
Investigators had not determined the cause of the crash but witnesses said they saw the bus brake and then swerve through lanes of traffic before overturning.
"It is a little early to determine whether it was driver error," California Highway Patrol spokesman Saul Gomez told KNBC. "We are worried more about the injured people than the actual investigation itself."
It was unclear whether other vehicles were involved in the crash. Several motorists pulled over on both sides of the freeway to lend a hand until rescue crews arrived.